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This invention relates to a viable commercial process for creating animal feed from the mass of waste food in the form of table scraps and spoilage thrown away by eating establishments such as cafeterias and restaurants and grocery stores and producers.
More people eat commercially prepared food out of the home than ever before. This is true not only in the United States, but in other parts of the world as well. Not only are more people eating out, but they eat out more often. This phenomena creates an enormous amount of waste; i.e., food scraps, over-ripe food, spoilage and animal parts discarded during food preparation, for disposal in landfills or incinerators. There is very little that can be done to recover this enormous store of protein in this potential food source and, since it commonly has a high water content, it is of little value as a fuel. Concurrently, in many parts of the world where the scraps are created and the spoilage occurs, there is also a dearth of food for feeding food source animals such as cattle, poultry, goats, lambs, and swine. This is particularly true in countries having only a small amount of land which can be devoted to farming or grazing, but yet there exists a dense population with a desire for meat. The land that is available, is most commonly used to grow food crops rather than the relatively inefficient growth of meat and protein from cattle. Many of their diets consequently are bereft of an effective protein source simply because the creation of edible protein is normally land intensive, with the exception of catfish farming. But, catfish is not the same.
The instant invention provides a process for recovering the protein values from these food sources and creating a protein-rich animal feed which can be used to create the animal meat protein which is lacking in the diets of so many people. This is particularly true in parts of Southeastern Asia where there is virtually no land available to grow this feed source.
While feed for meat-producing animals such as cattle does require some amount of real estate, even when in its greatest concentration such as a feed lot, if the feed lot can be located relatively close to the population center, then the transportation for the food scraps and spoilage to provide the source of protein for an animal feed would be minimized as would the time in transit, and there would be essentially no transportation costs involved in moving the processed animal food to the animals themselves for feeding.
While the prior art processes involve treating food-type vegetable waste for many purposes, none clearly address this problem in a meaningful way. One such process is described in U.S. Pat. No. 5,810,903, for a thermophilic aerobic fermentation of organic waste, which could be construed to include table scraps. The process involves the steps of pulping with water and then fermenting the mixture with microbes followed by an oxygenation step to enhance the growth of the microorganisms in the fermentation batch. Another process involves the degradation of organic waste by adding enzymes to a thermophilic aerobic degradation slurry made up of not more that 15% solids of microbially degradable material in the method described in U.S. Pat. No. 4,132,638. There the product of the process is a fertilizer or soil improver material from many different kinds of organic wastes including putrifial organic waste from communal kitchens.
A process for recovering fats, sugars, proteins, and starch from waste bakery products is described in U.S. Pat. No. 4,046,789, which involves various chemical reaction steps for dissolving, leaching and separating the various components of biscuit ingredients. Protein is recovered from food waste by microbial action to produce an animal feed or food supplement as described in U.S. Pat. No. 4,018,650. Here a protein source and carbohydrate source are brought together and subjected to microbial fermenting organisms to produce the protein cell.
U.S. Pat. No. 5,174,042 describes a garbage disposal device which utilizes a microwave heater to heat the garbage contained in the claimed garbage receptacle. This microwave heating drives the water out of the garbage and makes it somewhat less of a mess for removal to the location for pickup by the garbage truck.
As can be seen by the foregoing examples, many treatments have been applied in connection with the disposal of various wastes, including food waste. None address the desirable result of converting putrid vegetables and other food waste to a protein-rich feed for animals. However, the process described hereinafter provides steps for easily and economically processing food scraps and other sources of protein in food waste for use as an animal food to assist in the improvement of the protein content of the diet of populations through the production of feed for meat producing livestock and poultry.
A grain feed for livestock and other animals would contain about 10 to 12% protein. It has been found that the practice of this process produces a protein feed having a protein content of from about 20% to 28% protein, usually about 25% and, therefore, one would consider that the product of the process of this invention is a protein-rich food product. Even if it only produced an animal feed having about the same protein content as a grain feed, it accomplishes the objectives of a protein-rich feed in that it replaces with an otherwise useless waste, a product having a significant value for the purpose. Thus, the valuable result of this process is realized.
The process of this invention for producing a protein-rich animal feed is carried out by gathering the food scraps, usually from a restaurant, cafeteria, food processing plant or the like, or other spoiled or over-ripe vegetables and fruit, and transporting it to the processing facility. During the preparation of meat or preparing food for storage, freezing, canning or the like, objects are boned, gutted, trimmed or discarded. These, too, can be treated in the practice of this invention. At the facility, the table scraps and other protein-containing food waste, even animal entrails and bones, are collected in a holding tank until enough material for several hours of processing of the food waste is present. The most efficient use of this process assumes that the in-flow of the food waste, including table scraps, is relatively frequent and voluminous in order to keep the facility in motion. The food wastes are fed in contact with super-heated steam of from 110xc2x0 C. to about 160xc2x0 C. under elevated pressure, preferably about two atmospheres, to cook the food waste and reduce the microbial content. This contrasts with prior processes which encourage the microbial activity with heat, aeration and enzyme addition to aerobically degrade the food waste. It is in the practice of this invention that the food waste is maintained, not degraded.
The food waste is then minced, preferably ground to reduce the particle size to 3 mm or less. The steam remains present with the food waste during this grinding process to assure uniform heating and cooking, and since the steam condenses it creates a pumpable fluid stream of minced food waste, which then enters a conduit for transfer from the chopping stage to the next processing step while providing a residence time of about 30 minutes in the presence of the steam for continued cooking. This time is adjustable depending upon the make up of food waste in the feed. Steam, of course, condenses during the step, and the food waste being processed gathers even more water. From the cooking transport conduit, the food waste is then separated from the water by physical means such as a centrifuge, belt press, or screw press. This removes most (usually 50% to 75%) of the water and creates a semi-dry mass of the cooked food waste which now goes to a hot air dryer to remove the rest of the water and dry the food mass. In one embodiment, this dryer includes an internal mixing process to tumble the contents as they go through the vessel. This dryer is followed by a microwave treating zone, which uses radio waves to evaporate the remaining water and kill pathogens in, and assure sterilization of, the food waste. Alternatively, a commercially available dryer, microwave oven could be used. This later embodiment is preferred. After the sterilization step, the food waste is in condition to be sized and packaged for use as an animal feed.
The water and steam used are processed to maximize the energy recovery and to create a waste stream of water which is environmentally benign. The process also becomes more attractive through the installation of a co-generation plant which produces the steam for use in the process as well as electric power. The fuel of combustion for the boiler can be natural gas, oil, a biogas, coal, or wood. Of course, if the food waste reclamation project is used in conjunction with an anaerobic digester for the production of methane, that would be suitable fuel to use in the co-generation plant. This digester may also serve as an anaerobic digester in the process for converting manure to animal feed as described in co-pending patent application Ser. No. 09/788,087 (Atty. Dkt. No. 47425.1), filed on even date herewith. dr
FIG. 1 is a schematic flow sheet showing the process of this invention.